1. Field of the Invention
The present invention relates to a calendar for manufacturing webs of paper or a similar material. More specifically, the present invention relates to a calendar having two roll stacks, each having a deflection adjustment roll on at least one end, whose sleeve is supported by a deflection adjustment device on a fixed bracket.
2. Discussion of Background Information
In a known calender of this type, such as disclosed in DE 196 33 671 A1, two roll stacks of five rolls each are attached to a stanchion, one above the other, in a common vertical plane. The top roll and the bottom roll of each stack are deflection adjustment rolls. Each top roll is fixed to the stanchion. The bottom roll is fastened to a carriage that can be moved and loaded by a hydraulic cylinder. The roll sleeves are supported at their ends on the associated bracket. The bracket is fastened to either the stanchion or the carriage. There are also known deflection adjustment rolls of the sleeve lift type, for example, as disclosed in DE 30 04 913 C2. For these rolls, the roll sleeve is not supported on the bracket, but can be moved relative to the bracket so that the deflection adjustment device can be simultaneously used as a loading device.
The present invention a provides a calender that provides additional options for web treatment compared to the prior art.
In the present invention, as deflection adjustment roll of one roll stack and a deflection adjustment roll of a second roll stack are of the sleeve lift type. They are adjacent to each other, and can form an additional nip that can be closed by the sleeve lift. The effective direction of the deflection adjustment device alternatively points toward the associated roll stack or toward the other deflection adjustment roll.
If the effective direction is toward the associated roll stack, the calendar operates normally. However, if the effective direction is toward the other deflection adjustment roll, then an additional nip is formed, which can be used alone. If the two adjacent deflection adjustment rolls have an elastic cover, a matte satination is defined between the rolls. When manufacturing with the additional nip, the other rolls of the two roll stacks are not used, and can therefore be replaced or repaired. Thus, when one or more of the intermediary rolls needs to be repaired or replaced, the calendar can continue to operate using the adjacent deflection adjustment rolls.
Deflection adjustment devices are known in a wide variety of forms. For the most part, they function with hydrostatic support devices, particularly in the form of a series of support element that define the effective direction. It is therefore preferable that the deflection adjustment device of the present invention include a series of support elements, which can be moved through an angle (i.e., rotate) by an adjusting device. This minimizes the structural expense of the support device. In addition, a guide for the directed sleeve lift moves with the series of support elements.
As an alternative, the deflection adjustment device can include two series of support elements offset from each other. These support elements can be intentionally activated.
Preferably, the bearings for the bracket have at least one deflection adjustment roll cam with which the distance between adjacent deflection adjustment rolls can be changed. This cam can close the nip between the adjacent deflection rolls (the additional xe2x80x9cnipxe2x80x9d) if the sleeve lift alone is insufficient.
Preferably, the cams, together with the bracket, can be rotated through an angle by the adjusting device. Only one adjusting device is, therefore, needed to adjust the bracket and cams.
The two roll stacks preferably have a common central plane. This allows a common guide to be used on the stanchion.
Preferably, the common central plane extends obliquely to the horizontal. The resulting calendar has a height less than a 10-roll calendar with a vertical roll stack, and a length less than two 5-roll calenders with vertical roll stacks arranged next to each other.
In an alternative, the central planes of the two roll stacks can form an angle, particularly an acute angle, in relation to each other.
Preferably, the roll stacks have an odd number of rolls, each nip is defined by a hard roll and an elastic roll, and the deflection adjustment rolls that define the additional nip have an elastic cover. When using both roll stacks, this produces a glossy satination of the paper in which the two sides of the web side alternatively rest against the hard, smooth rolls. A matte satination is produced when only the additional nip is used.
The above noted benefits are particularly realized with combinations of roll stacks having 3, 5, or 7 rolls. Two roll stacks with 5 roll are preferred because of a high degree of uniformity in the paper web treatment.
In an exemplary embodiment, first and second roll stacks have first and second deflection adjustment rolls on an end thereof, respectively. Each of the first and second deflection adjustment rolls has a sleeve lift, and a sleeve supported by a deflection adjustment device on a fixed bracket. The first and second deflection adjustment rolls are adjacent to each other to define an additional nip therebetween that can be at least partially closed by the sleeve lift. An effective direction of the deflection adjustment device of the first deflection adjustment roll alternatively points toward the first roll stack and the second deflection adjustment roll, and an effective direction of the deflection adjustment device of the second deflection adjustment roll alternatively points toward the second roll stack and the first deflection adjustment roll.
According to a feature of the above embodiment, the deflection adjustment device of the first and second deflection adjustment rolls has a series of supporting elements that can be rotated by an adjusting device. Bearings for the bracket have at least one cam that can change a distance between the first and second deflection adjustment rolls. The adjusting device rotates the cam and the bracket.
In another feature of the above embodiment, the first and second roll stacks have a substantially common central plane, which preferably extends obliquely to a horizontal plane.
The first and second roll stacks may each have an odd number of rolls of alternative hard rolls and elastic rolls to define a plurality of nips therebetween, and the first and second deflection adjustment rolls have an elastic cover. The odd number is preferably 5.
According to another embodiment of the invention, a calendar for treating a material web includes first and second roll stacks having adjacent first and second deflection adjustment rolls on an end thereof, respectively, to define an additional nip therebetween. Each of the first and second deflection adjustment rolls have a deflection adjustment device. An adjusting device can move each of the deflection adjustment devices of the first and second deflection adjustment rolls to a first position in which an effective direction of each of the deflection adjustment devices of the first and second deflection adjustment rolls is toward the first and second roll stacks, respectively, and a second position in which the effective direction is toward the second and first deflection adjustment rolls, respectively. A closing device can open and close the additional nip when the deflection adjustment devices of the first and second deflection adjustment rolls are in the second position.
The deflection adjustment devices of the first and second deflection adjustment rolls preferably have a series of supporting elements that can be rotated by the adjusting device. The adjusting device includes bearings on a bracket having at least one cam that can change a distance between the first and second deflection adjustment rolls. The adjusting device rotates the cam and the bracket.
According to various features of the above embodiment, the first and second roll stacks preferably have a substantially common central plane. The substantial common central plane extends obliquely to a horizontally plane. The first and second roll stacks each have an odd number of rolls (preferably 5) of alternative hard rolls and elastic rolls to define a plurality of nips therebetween, and the first and second deflection adjustment rolls have an elastic cover.
A method for operating a calender is also provided. The calender includes first and second roll stacks having adjacent first and second deflection adjustment rolls on an end thereof, respectively, to define an additional nip there between. Each of the first and second deflection adjustment rolls have deflection adjustment device. The method includes moving each of the deflection adjustment devices of the first and second deflection adjustment rolls to a first position in which an effective direction of each of the deflection adjustment devices of the first and second deflection adjustment rolls is toward the first and second roll stacks, respectively, whereby the calendar can perform a first operation on the web. Each of the deflection adjustment devices of the first and second deflection adjustment rolls are moved to a second position in which the effective direction is toward the second and first deflection adjustment rolls, respectively. The first and second deflection adjustment rolls are moved toward each other to close the additional nip, whereby the calendar can perform a second operation on the web, the second operation being different from the first operation.
Moving each of the deflection adjustment devices of the first and second deflection adjustment rolls to the first position and moving each of the deflection adjustment devices of the first and second deflection adjustment rolls to the second position preferably includes rotating, by 180xc2x0, each of the deflection adjustment devices of the first and second deflection adjustment rolls.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawings.